No option to choose Left/Right click select in the 2.8 Preferences
You appear to have been using an older version of 2.8 with a custom keymap prior. Even through reinstalled, the custom keymap was kept.

The way hopefully not to get the Preferences Panel at the top of the Keymaps is to switch to a default keymap like Blender which strangely also has a few of the changed keys which were in the custom keymap.very strange